Loop forming device for stitch forming mechanism



June 3, 1952 v, BRlEM 2,599,226

LOOP FORMING DEVICE FOR STITCH FORMING MECHANISM Filed Oct. 7, 1948 z 26 a 24 I V 55 4 Inventor Eggerl V.. Bn'em Patented June 3, 1952 UNITED STATES PATENT OFFICE LOOP FORMING DEVICE FOR STITCH FORMING MECHANISM Claims.

This invention relates to improvements in the art of sewing, and more particularly to sewing with a needle having an eye, adjacent its point, such as is commonly employed in machine stitching.

In the operation of a conventional sewing machine the formation of the loop of thread between the eye of the needle and the work requires that the needle be projected through the work for the full length of the stroke of the needle bar and that the needle start on its return stroke before a loop is formed which may be engaged by the loop taking mechanism of the machine. As a result the loops so formed lie in various different positions relative to the axis of the needle and may in some instances lie wholly out ofthe path of movement of the loop taking mechanism with the result that a faulty stitch is produced in the work.

The primary object of this invention is to improve the quality of work produced on a sewing machine.

Another object is to increase the speed of machine sewing.

A further object is properly to orient successive loops, formed between the point of the needle and the work, with relation to the loop takin mechanism of a sewing machine.

Still another object is to effect a, cooling of the needle of a sewing machine during a high speed sewing operation.

The above and other objects may be attained by employing this invention which embodies among its features, feeding sewing thread through the eye of a needle at a speed which exceeds the speed of movement of the needle and immediately after the eye of the needle passes through the work during the penetrating stroke of the needle.

Other features include so orienting the thread 50 fed relative to the needle that the loop formed between the work and the needle lies in the path of movement of the loop taking mechanism of the sewing machine.

Still other features include directing an air blast axially through the major portion of a sewing machine needle to feed the thread and effect a cooling of the needle as the stitching thread is fed through the needle.

In the drawings:

Figure 1 is a diagrammatic end view of parts of a sewing machine equipped with apparatus designed for carrying out my invention, and;

Figure 2 is a fragmentary enlarged sectional view through the lower end of the needle bar and the sewing machine needle. s

Referring to the drawings in detail the sewing machine head is equipped with a conven tional rotary crank disc l0 carrying the conventional eccentric pin l2 which is coupled to my improved needle bar through the medium of a conventional connecting rod 14, and operating in conjunction with the rotary disc Ill and connecting rod I4 is the conventional thread take-up or tensioning and slackening arm I6. This is disclosed, for example, in the U. S. patent to A. Rontke, No. 989,538, April 11, 1911.

In accordance with the present invention, a cylinder I8 is mounted on the machine head adjacent the rotary disc l0, said cylinder It being provided intermediate its ends with a, port 23. Slidably mounted in the cylinder I8 is a piston 22 carrying a special needle bar 24. The needle bar 24 is fixed to the piston 22 to reciprocate therewith and is provided with a longitudinal internal bore 26, the upper end of which communicates with theinterior of the cylinder l8 below piston 22 through diametrically opposed ports 28 which open into the longitudinal bore 26 so that as the piston 22 reciprocates within the cylinder l8 air-will be expelled from the interior of the cylinder through the ports 28 and into the bore 26 of the needle bar 24. The lower end of the connecting rod [4 is pivotally connected as at 30 to the piston 22 so that the piston will be reciprocated within the cylinder in timed relation with the rotation of the disc H1. The stroke of the piston within the cylinder is such that when moving upwardly it passes beyond the port 20 so that air may be admitted through said port and subsequently with the down stroke of the piston ejected through the ports 28 into the interior of the needle bar 26. The needle bar is provided adjacent its lower end with an axial constricted passage 32, so that the air passing downwardly therethrough will be ejected therefrom in the form of a relatively high speed let for a purpose to be more fully hereinafter explained. Entering the end of the needle bar, and opening through one side thereof into the bore 26 is an elongated slot 34 in which is seated a thread guide 38 having an upwardly and outwardly extending arm 40 which is provided with an upwardly and outwardly extending passage 42, the upper end of which is flared as illustrated in Figure 2 to present a. smooth surface over which thread entering the passage 42 may pass into the interior of the needle bar.

Entering the lower end of the bore in the needle bar 24 is a machine needle designated generally 44 which comprises an elongated cylindrical body 46 having at one end a conventional needle point 48. The body 46 is provided with a longitudinal bore 50 which extends through the upper end of the needle in alignment with the constricted passage 32 of the needle bar 24, while the lower end of the passage 50 terminates in a lateral passage 52 which forms the eye of the needle. The body 43 of the needle is provided adjacent its upper end with diametrically opposed longitudinally extending elongated slots 54, into one of which the passage 42 opens, so as to enable the strand 56 of sewing thread to enter into the passage 56 of the needle 44, and pass outwardly through the eye 52assuggested in Figure 2; 'The parts, namely the'thread guide 38 and the needle 44 are held in proper position on the needle bar by a suitable clamp 58, and formed in the needle bar 24 diametrically ope, posite the slot 34 in substantial alignment; with. the inner end of the passage 42 in the thread guide 38 is an opening 6!], to serve as a'vent through which air may escape should. any back pressure be built up in the needle.

In operation the needle mounted in the needle bar as illustrated in Figure2 is reciprocated in the conventional rnanner'by the needle bar 24 and: thene'edlebar 'rciprocates, the piston 22 moving" in: the cyflin'denlfi"will compress the air admittedto' the'cylinder"through th'port 2G and elect it'thr oug lli ports '28-int'o the interior of-- the needle bar 24. the point of the needle 44 penetrates the work] and immediately after the eye of the needlep asses throughthework, the air directedthroughfthefconstricted passa e 3 2 will; rush" downwardly through the axial pas: sage tlil intli ne'ejdlefso that as the arm lfi' inoves downwardly to s'lacklenfththread- 5G between the the slackened threadbs through the passagetfl and eject it through the "eye" 52 substantially radial to needle 44, and with the thread ano cred inthe'work as suggested in" Figure 11 loop L beforin'cl whichbcause' of the direction of; the air blast issuing through the eye s. were. an e tat the m a n mechanism'of; the machine immediately below the worlgi Obviously the romance "ofthe loop Lwill begin sooinjas the eye's? passes through y? W rk; I A

Owing to the speed at which the air passing through the constricteii 'Ql ning s2 enters the needle 44. itjwill feed the thr'ad fi e thrcugh the t fll? a a spe l wticii" e h speeidbf movementfcffth needle" during its penetrating t1 troke. and on tan in p I w ll form stantially as soon as the eye 52 of the: needle Pass s throu h. the rk. 9 t atl'the 100p ak mech ni m ma e pe at d n timed letio' 'iii h' h rma iq o the eop o ak the loop while the needle is still advancing through the work." By employing thisdeyice it s. tv lo'usT hati lie epth. t Wi me te d e Pass s. b lo t Q I a e materially m she censeq eii b eps timing of the needle with the 'I ontaking'inechan ism, the ee o Q iti'a idn. of the-'ii i h ie e m t r a r imita e iter ar u it he t t the cq s or en e nder uent o the air issuing through the eye 5Z,':itis obvious that the duality ofwork may beimp'roved. "The air blast passing through the passage 5!! in the'needle 44 willalso srvets'cooi the needle during high speed sewing operations, thus increasing the useful life of the needle] Conventional t'ak'eups play out a slack in the thread a t tlie moment when the eye or thread openingpas'ses through the material. Ordinarily only parser the slack in the thread thus provided is pulled below the rhate'r'ia'lby the advancing needle,and'then'this'part'is'kinked into a loop by'the retraction of the needle. However, in the present 'ii'ew' method, "all of the slack payed out by" the tak'eup is drawn below' the material ar ist. teenage in't lt m it of air. The slack thread emerging from the opening in the needle immediately takes on the form of a growing loop between the lower side of the material and the opening 52, and when sufiicient slack has 'beefi payed outiby' the conventional takeiip ZO tb give the loop the desired size, it is picked up by the usual looper or other conventional loop manipulating mechanism. The processogblpwing. thev slack, provided in the needle threatihy the takeup, down through the needle to form a loop below the material, gives more pdsitiye results than the conventional method of draygingsomepflthe slack through the fabric by the advancing needle, and then kinking it into a loop by retraction of the needle.

While in the foregoing there has been shown and described thepreierred embodiment of this invention; it. is; be understood that minor changes in. thefdetails. of construction and arrangement of partsmay be resorted to without departing from the spirit and scope of the in- :yention as: claimed.

I-Iavingf'described the invention, What is claimed asnewis;

1 In. a sewing. machine. having. a loop taker, the combination. with a Yfirtically reciprocable needle" bar, afneedle, carried by the needle bar and reciprocable. thereby, said needle having. an axial bore tor passin thread through the needle and terminatin a lateral eyeforming passage near the, 1.13. 6. 15 DQimextension of, a loop offthethreadv out. at said n ed e a means for. automatically. filming a fluid blast through the bore and the. passa e; 01:? the eedle to feed the thread theretlircug'hfat. a speed which exceeds. the. speed of movement of the. needle so as to forma loopin. thethread outwardly of said passage for taking by said loop takerg said means comprising a pump. including a stationary cylinder, a piston reciprocable in the cylinder and connected to. thefupper end of the needle car, and means. connected to said piston to. recip the same and the needle bar, said needle bar having an axial. bore. communicating at its upper end with the cylinder. below. the, piston and at its lower end with the. bore of. the needle.

2. In a sewing machine, having a loop taker, the. combination witha vertically reciprocable needlev barfa needle, carried by.v the needle bar and reciprocable thereby S id needle having an axial bore for passing. a thread through the needle and terminating in a lateral eye-forming'passage near the needle. point for extension of7a"loo1: "of the thread out ofthe needle, and means for automatically forcing a fluid blast through the bore, and the passage of the needle to feed the. thread therethliough at a speed which exceeds the speedof; movement of the needle so as to form a loop inthe thread outwardly of said passage for taking by said loopjtaker, said means comprising. a pu p. including a stationary cylinder, a piston reoiprocable in the'cylinder and connected to the upper end OI the needle bar, and means. connected to said piston to reciprocate the same and the needle bansaid needle bar having an axial bore communicating at its upper end with the. cylinderbelQW the. piston and at its lower. end With the bore of. the needle, and a lateral thread uide carried by the lower end of the needle barifor leading the, thread into the bore of the needle.

3. In a sewingmachine. a yertically reciprocating hollow. needle, batia hollow needle carried thereby, andreciprpcating therewith and pro vided with'an .eye, and an air. compressor communicating with the interior of said bar to force air under pressure through said bar and needle to feed a thread through the needle and out of said eye, said compressor including a piston connected to said needle bar to reciprocate the same, and operating means for reciprocating said piston.

4. In a sewing machine, a vertically reciprocating hollow needle bar, a hollow needle carried thereby and reciprocating therewith and provided with an eye, an air compressor communicating with the interior of said bar to force air under pressure through said bar and needle to feed a thread through the needle and out of said eye, said compressor including a piston connected to said needle bar to reciprocate the same, a thread take-up mechanism, and a connection be- 6 tween said take-up mechanism and said piston for operating said piston in timed relation to operation of said take-up mechanism.

5. The combination according to claim 3 including a lateral thread guide carried by said bar and leading into said needle for leading a thread into the needle.

EGGERT V. BRIEM.

EEFERENfiES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,919,67 Wenczel July 25, 1933 2,432,285 Christensen Dec. 9, 1947 

